1. Field of the Invention
The present invention relates to a system for recycling resinous materials from resin mold products recovered from discarded apparatuses (such as home electric appliances, electronic devices or cars), more particularly to a crushing system for crushing polymer parts obtained by disassembling the recovered products to reduce the volume thereof; a classifying system for classifying the resinous materials into their kinds, preferably into kinds of fire retardants added thereto; and a cleaning system for removing foreign matters such as coated films, labels or seals applied to the products or other contamination thereof.
2. Description of the Related Art
Plastics light in weight and excellent in mechanical strength have often been used for home electric appliances, OA apparatuses, communication apparatuses or others as internal parts or external casings thereof. From a point of view of the environmental protection, the conversion from a mass-production/mass-scrap economy in the past to a circulation type economy is required. In such a recent trend, a full-scale recycle of resinous products has been urgently demanded; for example, the recycling of home electric appliances has been obligated by law. However, regarding the material recycle in which the resin mold products are recovered and reused as resinous materials, it is done solely in a case wherein it is possible to specify to some extent what kind of resin is used, because there is a problem peculiar to the resin in that if different kinds of resins are mixed together, functions inherent to the resin are significantly damaged. Accordingly, a resin recycling system is desired, which is capable of correctly classifying various kinds of resinous products used in the discarded appliances or apparatuses and regenerating the same as fresh resinous materials for the home electric appliances, OA apparatuses or communication apparatuses.
To proceed a high-quality recycling, it is necessary to correctly identify and classify materials of resin mold products containing various kinds of additives including fire retardant. Regarding the identification of materials of the resin mold products, a high-performance resin identification device has recently been developed, and is becoming reality. This device, however, necessitates a considerable care on the operation, maintenance and inspection thereof as well as it is expensive in cost. The most effective method for identifying materials of the resin mold products solely from a point of view of the material identification is to provide such a resin identification device in each of the disassembly factories. This method is, however, problematic from the economical view point or a view point of stable operation of the system.
To operate the above-mentioned resin identification device under the stably controlled condition, it is desirable to provide the disassembly factory for recovering the resin mold products at a position different from that of the resin identification device. In such a case, it is necessary to convey the resin mold products from the disassembly factory to the position at which the resin identification device is provided.
However, the resin mold products obtained from the discarded apparatuses have various shapes and sizes distributed from a small one to an extremely large one. Therefore, if they are packed into a box or a bag while maintaining their shapes, the physical transportation cost becomes wasteful since a bulk specific weight is very small to reduce a weight relative to a volume thereof. Accordingly, it is desired to crush the resin mold products into pieces having an economically preferable size (a size capable of achieving a proper transportation efficiency). As a crusher used for this purpose, it is possible to use a commercially available crusher such as a hammer mill, a cutter mill, a two-axis crusher and the like, which is capable of crushing the resin mold products into pieces having about 50 mm or less in size.
However, the resin mold products recovered from disassembling appliances have various sizes as set forth above. In order to load all of the resin mold products and crush them into pieces having about 50 mm or less in size, it becomes necessary to provide a very big crusher having a loading opening. Since these equipment is costly, there is a problem that it is economically impossible to install such expensive equipment at each of small factories.
Further, if the resin mold products are crushed altogether by such means, however, many of the resin mold products formed of different kinds of resins are crushed in a mixed state, and, as a result, it is necessary to identify crushed pieces in which many kinds of resins exist using an identification apparatus. Although such identification is possible in principle, industrialization thereof is difficult in practice because it is necessary to respectively identify kinds of resins of a large number of crushed pieces and classify the same into the respective materials after the identification.
In addition, to economically realize the material recycling of high-quality resinous materials, it is necessary to classify kinds of resins containing various additives such as fire retardant at a high accuracy and a high speed. As a method for classifying the kinds of resins, a technique using, for example, a near infrared ray absorption has been known and various devices are marketed. However, this method hardly identifies kinds of resins with many identification errors and is unsuitable for the high accuracy and high speed identification. Another method utilizing intermediate infrared absorption has been also known. Although this method is capable of identifying not only kinds of resins but also those of additives such as fire-retardant at a high accuracy, there is a problem in that a long time is required for the identification and therefore unsuitable for a high speed processing.
On the other hand, the recovered resinous products may be coated with films, applied with labels or the like or carry various contaminants, which are liable to enter the-resin during the treatment of the resinous products to result in a problem to significantly deteriorate the characteristic of the resin to be reused.
Although various trials have been attempted for removing foreign matters carried on the surface of the resinous product, for example, by a mechanical method and the separation or removal with a solvent, there is a problem in either cases. For instance, if the removal of the coated film or the label is intended by using a crusher such as a ball mill, the resin is softened due to heat generated by the friction during the crushing operation, which disturbs the resin removal or causes the re-adhesion of the foreign matters once removed. Also, there is another method wherein the foreign matters are dissolved with a solvent and then separated and removed from the resin. This method, however, has a serious problems in that the used solvent must be regenerated or discarded, and also has other problems in that an apparatus used therefor is complicated in structure and unfavorable from the economical point of view.
There is a still further method for removing the coated film or labels, called as a dry blast treatment, wherein an abrasive material such as sands or metallic particles is used for scraping off the foreign matters from the surface of the resinous product. According to this method, however, particles of the abrasive material may stick into the surface of the resinous product and remain as they are as new foreign matters. Also, the resin may be softened by heat generated due to the friction of the abrasive material and cause the re-adhesion of the foreign matters once removed.